Exchange rates are quoted for today, but some of the most important questions are about the past. What was the dollar–euro rate on the day you invoiced a client? What did the euro cost when you booked that trip six months ago? How much has a currency really lost over five years? Here is how to find and use historical rates properly.
Why you might need a historical rate
- Taxes: many tax authorities require you to convert foreign income or gains at the rate on the transaction date (or a yearly average rate, depending on the country and the tax).
- Invoicing and accounting: if you bill in a foreign currency, your books record the value at the exchange rate on the invoice date, and the difference at payment becomes an exchange gain or loss.
- Insurance and claims: losses abroad are often assessed at the rate on the loss date.
- Research and curiosity: comparing prices across time only makes sense at consistent rates.
Where to get reliable historical rates
The most widely used free sources are central-bank reference rates. The European Central Bank publishes daily reference rates for around 30 major currencies against the euro, going back to 1999, and many national central banks publish their own daily fixings. Fxverter's charts are built on exactly this kind of public reference data.
Rules of thumb when picking a source:
- Use a single consistent source for the whole calculation; mixing sources creates false gains and losses.
- Beware of weekends and holidays: reference rates are published on business days only. For a Saturday transaction, most conventions use the previous business day — check which convention your accountant or authority expects.
- For currencies with official pegs or multiple rates, the official reference rate may differ substantially from the street rate you actually paid. Document which one you are using.
- Very old or exotic pairs may only exist as cross rates via a third currency (typically the dollar or euro); that is normal and usually how they were always quoted.
Why sources disagree
Look up the same date on two websites and you will often see slightly different numbers. This is normal, and there are three reasons:
- Different fixings: the ECB reference rate, the London 4pm fix and a retail provider's daily rate are all "the rate", captured at different moments under different rules.
- Buy vs sell vs mid: a historical series may show mid-market rates while your receipt shows the customer rate, which includes a margin.
- Averaging windows: "annual average rate" can mean the average of daily rates or a weighted average — the results differ slightly.
For most personal purposes the differences are small. For tax filings, use the source your authority names; when none is named, a central-bank reference series is the defensible default.
Reading a rate table correctly
A rate of 1 USD = 0.92 EUR on one site and 1 EUR = 1.087 USD on another is the same fact written in two directions. When you compare historical data, always check which direction the quote is expressed and which currency is the base. A 10% move in EUR/USD and a 10% move in USD/EUR are very different events — one is a rise of the euro, the other is a fall of almost exactly 9.1% of the dollar, because reciprocal percentages are not symmetric.
Long horizons: what history can and cannot tell you
Over years, currency charts look dramatic — emerging-market currencies can lose half their value against the dollar within a decade, while major pairs oscillate in ranges. Three cautions:
- Past ranges are not guarantees. Pairs that "always" traded between two levels have broken out of those levels repeatedly — 2022 pushed EUR/USD to parity after two decades above it.
- Inflation matters more than the chart. A currency that "held steady" while domestic prices doubled has still lost half its purchasing power. Nominal rates and real value are different questions.
- Fixed and managed currencies lie politely. A flat line can mean genuine stability or a controlled rate that the black market disagrees with. For pegged currencies, look for news of devaluations rather than trusting the flat chart.
Practical workflow for a tax date
1. Note the exact transaction date and the currency pair and direction you need.
2. Pick your reference source (the one your authority or accountant prefers, otherwise a central-bank series).
3. If the date is a weekend or holiday, apply the previous-business-day convention.
4. Convert, then save a screenshot or note of the source, series name and date with your records. Future-you, or an auditor, will want the provenance.
Historical rates turn vague memories into precise numbers. The trick is not finding data — it is using one consistent, citable source and writing down which one you used.